Arrangement for scattering auxiliary substances in vacuum valves



B. LOEWE May I, 1934.

ARRANGEMENT FOR SCATTERING AUXILLARY SUBSTANCES IN VACUUM VALVES Filed March 7, 1929 a. 9 a amma? X 5514.

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Patented May 1, 1934 ARRANGEMENT FOR SCATTERING AUXIL- IARY SUBSTANCES IN VACUUM VALVES Bernhard Loewe, Berlin, Germany Application March 7, 1929, Serial No. 345,127

' 'In Germany March 7, 1928 3 Claims.

This invention relates to a method of and means for applying in an electron discharge device electron-emission material and vaporizing the same to coat the electron-emission electrode of the device with such material.

In further developing the invention described in patent application filed February 28, 1929, Serial No. 343,337, it was discovered that it is advisable to remove the gas and water from the electron emission material before it is introduced into the electron valve system. This results in the advantage that the compound becomes very compact. One way of performing the operation is to pour the reaction mixture while it is in a temporary liquefied state into molds. If it is heated in the molds, it will be firmly sealed in the molds, thus obviating its being pressed into molds. If barium oxide and silicon are used, for instance, the compound upon being heated to a zopoint below the reaction temperature, may be liquefied and poured into moulds or, if the heating is carried out in these moulds, firmly sealed into the same. The heating of the compound as a preparatory treatment is an esential part of the invention. If the heating is effected in vacuum, the compound may be freed from water and gases to a very high degree. The compound thus subjected to a preparatory treatment may be very simply handled in the manufacture of the emission cathode.

The degassed and dehydrated compound may in some cases be sealed firmly to the anode itself or to a holder plate fixed thereto, thus obviating the use of independent containers for the compound and objections to the use thereof.

It has further been discovered that it is sometimes advisable to pulverize the compound after shrinkage.

In cases where the temperature required for starting the reaction is so high that certain metal elements of the electrode system of the valve may be unduly heated, the reaction compound is best heated by itself by the passage of current, for instance, by resistance heating after the gas of the metal elements has previously been separately discharged.

In the example above described of the reaction of barium oxide and silicon the contracted reaction compound is sufficiently conductive to be quickly raised to the necessary temperature upon the passage of current. It is advisable in other cases to admix conductive material or to attach the compound to a semi-conductor or conductor to be heated by resistance heating.

The arrangement will be particularly favourable if the compound is pressed or poured in the form of small rods, or is sealed in or contracted in the manner above described and subsequently is fixed conductively between two suitable elements of the system in such a manner that the current may be supplied from the outside. If that is done, the metal elements of the readily assembled valve may by themselves be deprived of gas, e. g., by eddy current heating, the temperatures being suited to the metals to be deprived of gas. After completion of this operation the desired reaction may be effected by direct resistance heating. Any necessary disconnections will then take place either by the reaction compound scattering as such, or losing its conductivity, or by the conductive connection at a point specially provided for this purpose being disconnected by current overloading.

My invention may be best understood with reference to the accompanying drawing, in which:

Fig. 1 shows an exemplary embodiment of the invention for sealing the activation or electronemission compound into a container. 1 is the container, which is generally metallic, 2 the electron-emission compound after the contraction.

Fig. 2 illustrates a cross section of a single anode plate 3 of curved cross-section whose inside contains at 4 the electron-emission compound previously contracted and deprived of gas. The mode of use of this anode plate in an electrode system of an electron discharge device will be readily understood.

Fig. 3 shows a section through an electron discharge device with one electrode system into which an electron-emission compound of rodshape is introduced. 5 is the anode, 6 the grid, 7* the filament, 9 the electron-emission compound of rod-shape and in the form of a coating about a conductor wire 12. At its ends 8 and 10 the wire 12 is connected with the current leads, preferably with suitably selected electrode leads of the system, and at a suitable point of the manufacturing process is brought to reaction by means of resistance heating.

Fig. 4 shows an exemplary embodiment for an electron-emission rod of the type shown in Fig. 3 in which the compound 9= is applied as a coating about a conductor 12*- in the form of an electric heating spiral. The rod here is employed in the same manner as the rod in Fig. 3.

I claim:

1. Those steps in the preparation of an emission compound for coating the cathode of a vacuum tube which consist in preparing a hydrous reaction mixture of barium oxide and silicon having a fusing point below the reaction temperature, and heating the mixture to free the mixture from water and gases and to fuse the same, the heating temperature being below the reaction temperature. v

2. Those steps in the preparation of an emission compound for coating the cathode of a vacuum tube which consist in preparing a hydrous reaction mixture of barium oxide and silicon having a fusing point below the reaction temperature, heating the mixture to free the mixture from water and gases and to fuse the same, the heatr BERNHARD LOEWE. 

